1. Technical Field
The present invention relates to a fluid supply mechanism, a method of supplying fluid to a fluid ejection head, and a fluid ejection device that suctions fluid from a main tank such as an ink cartridge to a subtank, and then supplies fluid from the subtank to the fluid ejection head.
2. Related Art
An ink supply system for an inkjet printer that has an ink cartridge or other main tank disposed on the printer frame, and a subtank mounted on a carriage with the inkjet head, supplies ink from the subtank to the main tank when printing, and refills the subtank with ink from the main tank while the inkjet head is parked at the home position, is known from the literature. Japanese Unexamined Patent Appl. Pub. JP-A-2010-626 teaches an inkjet printer that has this type of ink supply system.
The inkjet printer taught in JP-A-2010-626 supplies ink to the subtank using an ink pump having a diaphragm. This ink pump suctions ink by displacing the diaphragm with a rocking lever. When the inkjet head moves to the home position, the lever rocks such that the free end of the lever contacts a fixed member on the home position side, thereby lifting the diaphragm, increasing the capacity of the ink chamber, and suctioning ink. A self-sealing unit for blocking transmission of pressure fluctuations to the upstream side is disposed between the subtank and the inkjet head. When the inlet to the self-sealing unit is opened by negative pressure on the inkjet head side, ink is supplied from the subtank to the inkjet head through the self-sealing unit.
Performing the ink refill operation during printing when the regular flushing operation is performed in this ink supply system has also been proposed. Because there is no particular need to return the inkjet head to the home position in this case, the ink supply can be efficiently replenished without causing a drop in throughput. However, because the ink in the subtank is consumed before the regular flushing interval when printing a pattern that consumes a large amount of ink, the ink refill operation must be performed before the regular flushing operation and the printing operation is thus interrupted. More specifically, because an inkjet line head has many nozzles, ink consumption is great, and the possibility that the ink will be depleted before the regular flushing interval is great. Printing is thus interrupted more frequently and throughput drops.